Flink自定义 Sink 函数从kafka往kudu写数据

1、flink Sink简介

flink 中有两个重要的概念，Source 和 Sink ，Source 决定了我们的数据从哪里产生，而 Sink 决定了数据将要去到什么地方。
flink 自带有丰富的 Sink，比如：kafka、csv 文件、ES、Socket 等等。
当我们想要使用当前并未实现的 Sink 函数时，可以进行自定义。

2、自定义 Sink 函数

这里主要自定义写入 kudu 的 kuduSink。
自定义sink需要我们实现 SinkFunction，或者继承 RichSinkFunction

package TestKudu;

import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;
import org.apache.kudu.Schema;
import org.apache.kudu.Type;
import org.apache.kudu.client.*;
import org.apache.log4j.Logger;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Map;

public class SinkKudu extends RichSinkFunction<Map<String, Object>> {

    private final static Logger logger = Logger.getLogger(SinkKudu.class);

 private KuduClient client;
 private KuduTable table;

 private String kuduMaster;
 private String tableName;
 private Schema schema;
 private KuduSession kuduSession;
 private ByteArrayOutputStream out;
 private ObjectOutputStream os;

 public SinkKudu(String kuduMaster, String tableName) {
        this.kuduMaster = kuduMaster;
 this.tableName = tableName;
 }

    @Override
 public void open(Configuration parameters) throws Exception {
        out = new ByteArrayOutputStream();
 os = new ObjectOutputStream(out);
 client = new KuduClient.KuduClientBuilder(kuduMaster).build();
 table = client.openTable(tableName);
 schema = table.getSchema();
 kuduSession = client.newSession();
 kuduSession.setFlushMode(SessionConfiguration.FlushMode.AUTO_FLUSH_BACKGROUND);
 }

    public void invoke(Map<String, Object> map) {
        if (map == null) {
            return;
 }
        try {
            int columnCount = schema.getColumnCount();
 Insert insert = table.newInsert();
 PartialRow row = insert.getRow();
 for (int i = 0; i < columnCount; i++) {
                Object value = map.get(schema.getColumnByIndex(i).getName());
 insertData(row, schema.getColumnByIndex(i).getType(), schema.getColumnByIndex(i).getName(), value);
 }

            OperationResponse response = kuduSession.apply(insert);
 if (response != null) {
                logger.error(response.getRowError().toString());
 }
        } catch (Exception e) {
            logger.error(e);
 }
    }

    @Override
 public void close() throws Exception {
        try {
            kuduSession.close();
 client.close();
 os.close();
 out.close();
 } catch (Exception e) {
            logger.error(e);
 }
    }

    // 插入数据
 private void insertData(PartialRow row, Type type, String columnName, Object value) throws IOException {

        try {
            switch (type) {
                case STRING:
                    row.addString(columnName, value.toString());
 return;
 case INT32:
                    row.addInt(columnName, Integer.valueOf(value.toString()));
 return;
 case INT64:
                    row.addLong(columnName, Long.valueOf(value.toString()));
 return;
 case DOUBLE:
                    row.addDouble(columnName, Double.valueOf(value.toString()));
 return;
 case BOOL:
                    row.addBoolean(columnName, (Boolean) value);
 return;
// case INT8:
// row.addByte(columnName, (byte) value);
// return;
// case INT16:
// row.addShort(columnName, (short) value);
// return;
 case BINARY:
                    os.writeObject(value);
 row.addBinary(columnName, out.toByteArray());
 return;
 case FLOAT:
                    row.addFloat(columnName, Float.valueOf(String.valueOf(value)));
 return;
 default:
                    throw new UnsupportedOperationException("Unknown type " + type);
 }
        } catch (Exception e) {
            logger.error("数据插入异常", e);
 }
    }
}

KuduSink 函数, 继承了 RichSinkFunction，重写了 open、close 和 invoke 方法，在 open 中进行 kudu 相关配置的初始化，在 invoke 中进行数据写入的相关操作，最后在 close 中关掉所有的开关。

3、测试样例

package TestKudu;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

import java.util.HashMap;
import java.util.Map;

public class SinkTest {

    public static void main(String []args) throws Exception {

        // 初始化 flink 执行环境
 StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

 // 生成数据源
 DataStreamSource<UserInfo> dataSource = env.fromElements(new UserInfo("001", "Jack", 18),
 new UserInfo("002", "Rose", 20),
 new UserInfo("003", "Cris", 22),
 new UserInfo("004", "Lily", 19),
 new UserInfo("005", "Lucy", 21),
 new UserInfo("006", "Json", 24));

 // 转换数据 map
 SingleOutputStreamOperator<Map<String, Object>> mapSource = dataSource.map(new MapFunction<UserInfo, Map<String, Object>>() {

            public Map<String, Object> map(UserInfo value) throws Exception {
                Map<String, Object> map = new HashMap<String, Object>();
 map.put("userid", value.userid);
 map.put("name", value.name);
 map.put("age", value.age);
 return map;
 }
        });

 // sink 到 kudu
 String kuduMaster = "";
 String tableInfo = "";
 mapSource.addSink(new SinkKudu(kuduMaster, tableInfo));

 env.execute("sink-test");
 }
}